In general, lighting devices are provided in a vehicle in order to stably secure visibility of a driver even when illumination is low at the periphery of the vehicle at the time of driving a vehicle, and among the lighting devices, an LED head lamp using a light emitting diode (LED) as a light source of a head lamp has been developed.
Here, the LED is a diode that emits excess energy as light when injected electrons and holes are coupled again, emits red light or green light, and is mainly used as a light source using advantages of low pressure and low electric power consumption.
Particularly, an LED array is a type of a light source formed by mounting a plurality of LEDs, and may directly implement various beam patterns by selectively turning on the plurality of LEDs.
Therefore, the LED array may be applied to a head lamp and a rear lamp of the vehicle so as to be effectively used to implement various beam patterns.
In this regard, as a related art, there is Korean Patent Application Laid-Open No. 10-2005-0103391 entitled ‘Light Distribution Structure of LED Head Lamp for Vehicle’.
In the light distribution structure of an LED head lamp for a vehicle, a light concentration structure of the LED head lamp is described, as illustrated in FIG. 1.
When describing the light concentration structure of the LED head lamp with reference to FIG. 1, a light concentration structure 10 of the LED head lamp may include an LED light source 11, a reflection mirror 12 which adjusts a direction of light from the LED light source 11, a lens 13 which protects the LED light source 11, and a shade or shield 14 which cuts off light emitted toward an opposite vehicle so as to prevent light blindness to a driver in an oncoming vehicle.
However, an L-shaped beam pattern, which is implemented by the shield 14, may implement a glare free high beam on the basis of both interfaces of left and right head lamps, but there is a drawback in that visibility deteriorates because the light corresponding to an intermediate region exists as a dark zone|[s1]. There is a problem in that light efficiency is decreased due to light shielding when the shield 14 is used.
Accordingly, as a light source of the head lamp for a vehicle, an LED light source, which directly emits light to the lens 13, is used.
LED elements, which are used as the LED light source, are designed to have the same size, and emit light to a front side of the vehicle.
Particularly, when a high beam is emitted to an oncoming vehicle or a preceding vehicle using the LED elements installed to have the same size, the LEDs disposed in a predetermined region are turned on and off. Here, the oncoming vehicle refers to a vehicle that moves toward another moving vehicle while facing the moving vehicle, and the preceding vehicle means a vehicle that precedes the moving vehicle on a road on which the moving vehicle moves.
However, as illustrated in FIG. 2, when the high beam is emitted so as to correspond to a location of an oncoming vehicle 3 or a preceding vehicle 4, the LED elements having the same light emitting area are turned on and off, and thereby, the LED element has a limit to implement a function of preventing light blindness.
That is, as illustrated in FIG. 2, there is a problem in that when the LED elements having the same light emitting area are turned on and off so as to correspond to a location where the oncoming vehicle 3 moves, even though the LED elements, which corresponds to an excessive region in order to screen the oncoming vehicle 3, are turned on and off so as to prevent light blindness to the driver in the oncoming vehicle 3, visibility of a driver in the moving vehicle 2 deteriorates.
When describing in more detail with reference to FIGS. 2 and 3, in the case of light A emitted to the oncoming vehicle 3 positioned at a distal location, a screen angle of the light emitted from the vehicle 2 becomes narrow. As the oncoming vehicle 3 moves, the screen angle of the light emitted from the vehicle 2 is increased like light B.
That is, the screen angle for preventing light blindness against the oncoming vehicle 3 is slowly increased in a range of 1,000 to 200 m, and then rapidly increased from a location of 200 m.
Therefore, in a case in which the moving vehicle 2 has the LED elements having the same light emitting area as the light source, it is possible to prevent light blindness to the driver in the oncoming vehicle 3 when the oncoming vehicle 3 is moving, but there is a problem in that visibility of the driver in the vehicle 2.